A key finding in the literature on authoritarian regimes is that leaders frequently rely on ruling parties to stay in power, but we lack systematic ways to measure autocratic party strength. As a result, it is not clear how often ruling parties are actually strong and capable of carrying out important functions. This article demonstrates that strong ruling parties are much rarer than typically assumed. Using a global sample of dictatorships from 1946-2008, I show that most ruling parties are unable to survive the death or departure of the founding leader. This is true even of many parties that have been coded as part of single-party regimes. While strong parties may be key to durable authoritarianism, relatively few parties are actually strong.